Print version of Make

Print a warning with the version of Make used by the system to help
debug/reproduce Makefile issues.

Change-Id: Ia64e607d2b258044e3bfb2a9b443e59b123daad4
diff --git a/Makefile b/Makefile
index c244413..5a18326 100644
--- a/Makefile
+++ b/Makefile
@@ -18,6 +18,8 @@
 MAKEFLAGS += --jobs=$(CPUS)
 SHELL ?= $(shell which bash)
 
+$(warning MAKE_VERSION=$(shell $(MAKE) --version))
+
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